The other donors were said to include a music producer and the author and libel reform campaigner Simon Singh, who donated £1,000 each.

Hacked Off has not previously revealed the names of individual donors and has come under fire from some sections of the press for its apparent secrecy.

On its website it reveals only a £50,000 grant from the Joseph Rowntree Reform Trust and £20,000 it says it is set to receive from the Journalism Foundation, an independent charity set up by the Lebedevs that funds projects promoting free and independent journalism.